U.S. patent application number 14/424416 was filed with the patent office on 2016-02-18 for methods of preparing electrode assembly and secondary battery.
This patent application is currently assigned to LG CHEM, LTD.. The applicant listed for this patent is LG CHEM, LTD.. Invention is credited to Chang Bum AHN, Ki Hong MIN, Young Joo YANG.
Application Number | 20160049687 14/424416 |
Document ID | / |
Family ID | 53031377 |
Filed Date | 2016-02-18 |
United States Patent
Application |
20160049687 |
Kind Code |
A1 |
YANG; Young Joo ; et
al. |
February 18, 2016 |
METHODS OF PREPARING ELECTRODE ASSEMBLY AND SECONDARY BATTERY
Abstract
Provided are a method of preparing an electrode assembly
suitable for preparing a secondary battery having a structure that
may increase a degree of freedom in the design of a device in which
the secondary battery is installed, and a method of preparing a
secondary battery.
Inventors: |
YANG; Young Joo; (Daejeon,
KR) ; MIN; Ki Hong; (Daejeon, KR) ; AHN; Chang
Bum; (Daejeon, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LG CHEM, LTD. |
Seoul |
|
KR |
|
|
Assignee: |
LG CHEM, LTD.
Seoul
KR
|
Family ID: |
53031377 |
Appl. No.: |
14/424416 |
Filed: |
September 18, 2014 |
PCT Filed: |
September 18, 2014 |
PCT NO: |
PCT/KR2014/008682 |
371 Date: |
February 26, 2015 |
Current U.S.
Class: |
29/623.4 ;
29/623.1 |
Current CPC
Class: |
H01M 10/0565 20130101;
H01M 10/0436 20130101; H01M 2220/30 20130101; H01M 10/052 20130101;
H01M 10/0585 20130101; H01M 2/1673 20130101; H01M 4/742 20130101;
H01M 4/13 20130101; H01M 2004/025 20130101; H01M 2/18 20130101;
Y02E 60/10 20130101 |
International
Class: |
H01M 10/04 20060101
H01M010/04 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 26, 2013 |
KR |
10-2013-0114247 |
Aug 21, 2014 |
KR |
10-2014-0108814 |
Claims
1. A method of preparing an electrode assembly, the method
comprising: forming recessed portions recessed from edges of a
first electrode and a second electrode toward inner sides thereof
(S11); forming a unit structure having a four-layer structure, in
which the first electrode, a first separator, the second electrode,
a second separator are sequentially stacked, or a structure in
which the four-layer structures are repeatedly stacked, or having
the four-layer structure or a structure, in which the four-layer
structures are repeatedly arranged, by stacking two kinds or more
of radical units, in which the first electrode, the first
separator, the second electrode, and the second separator are
alternatingly disposed and integrally combined, one by one in a
predetermined sequence (S20); forming recessed portions in the
first separator and the second separator by cutting regions of the
first separator and the second separator included in the unit
structure corresponding to the recessed portions with a margin
(S31); and forming an electrode assembly by stacking the plurality
of unit structures to allow the recessed portions of the adjacent
unit structures to face each another (S41).
2. The method of claim 1, wherein the recessed portions formed in
any one of the unit structures have a different size from that of
the recessed portions formed in the adjacent unit structure.
3. The method of claim 2, wherein the size of the recessed portions
gradually increases or decreases from a top surface of the
electrode assembly to a bottom surface thereof.
4. A method of preparing an electrode assembly, the method
comprising: forming through holes at inner sides of a first
electrode and a second electrode (S12); forming a unit structure
having a four-layer structure, in which the first electrode, a
first separator, the second electrode, a second separator are
sequentially stacked, or a structure in which the four-layer
structures are repeatedly stacked, or having the four-layer
structure or a structure, in which the four-layer structures are
repeatedly arranged, by stacking two kinds or more of radical
units, in which the first electrode, the first separator, the
second electrode, and the second separator are alternatingly
disposed and integrally combined, one by one in a predetermined
sequence (S20); forming through holes in the first separator and
the second separator by cutting regions of the first separator and
the second separator included in the unit structure corresponding
to the through holes with a margin (S32); and forming an electrode
assembly by stacking the plurality of unit structures to allow the
through holes of the adjacent unit structures to face each another
(S42).
5. The method of claim 4, wherein the through holes formed in any
one of the unit structures have a different size from that of the
through holes formed in the adjacent unit structure.
6. The method of claim 5, wherein the size of the through holes
gradually increases or decreases from a top surface of the
electrode assembly to a bottom surface thereof.
7. The method of claim 1, wherein the unit structure is formed by
bonding the electrodes and the separators to one another.
8. The method of claim 7, wherein the bonding of the electrodes and
the separators is performed by applying pressure or applying heat
and pressure to the electrodes and the separators.
9. The method of claim 7, wherein the unit structure is formed by
laminating the electrodes and the separators.
10. The method of claim 7, wherein surfaces of the separators are
coated with a coating material having adhesiveness.
11. The method of claim 10, wherein the coating material is a
mixture of inorganic material particles and a binder polymer.
12. The method of claim 10, wherein both sides of the first
separator respectively facing the first electrode and the second
electrode are coated with the coating material and only one side of
the second separator facing the second electrode is coated with the
coating material.
13. The method of claim 10, wherein both sides of the first
separator respectively facing the first electrode and the second
electrode are coated with the coating material and one side facing
the second electrode and an opposite side thereto of the second
separator are coated with the coating material, wherein the
plurality of unit structures included in the electrode assembly are
bonded each other by the coating material of the second
separator.
14. (canceled)
15. (canceled)
16. (canceled)
17. (canceled)
18. (canceled)
19. (canceled)
20. (canceled)
21. The method of claim 1, further comprising a fixing part fixing
a side or a front side of the electrode assembly.
22. The method of claim 21, wherein the fixing part is realized by
using a polymer tape taping the side or the front side of the
electrode assembly.
23. A method of preparing a lithium secondary battery, the method
comprising steps of: forming recessed portions recessed from edges
of a first electrode and a second electrode toward inner sides
thereof (S11); forming a unit structure having a four-layer
structure, in which the first electrode, a first separator, the
second electrode, a second separator are sequentially stacked, or a
structure in which the four-layer structures are repeatedly
stacked, or having the four-layer structure or a structure, in
which the four-layer structures are repeatedly arranged, by
stacking two kinds or more of radical units, in which the first
electrode, the first separator, the second electrode, and the
second separator are alternatingly disposed and integrally
combined, one by one in a predetermined sequence (S20); forming
recessed portions in the first separator and the second separator
by cutting regions of the first separator and the second separator
included in the unit structure corresponding to the recessed
portions with a margin (S31); forming an electrode assembly by
stacking the plurality of unit structures to allow the recessed
portions of the adjacent unit structures to face each another
(S41); and accommodating the electrode assembly in a pouch case and
forming regions of the pouch case other than a vertical projection
plane of the electrode assembly as fused portions (S50).
24. The method of claim 23, wherein step S50 comprises a process of
cutting a smaller area than the recessed portion of the first
separator and the second separator out of the region of the fused
portions corresponding to the recessed portions.
25. A method of preparing a lithium secondary battery, the method
comprising steps of: forming through holes at inner sides of a
first electrode and a second electrode (S12); forming a unit
structure having a four-layer structure, in which the first
electrode, a first separator, the second electrode, a second
separator are sequentially stacked, or a structure in which the
four-layer structures are repeatedly stacked, or having the
four-layer structure or a structure, in which the four-layer
structures are repeatedly arranged, by stacking two kinds or more
of radical units, in which the first electrode, the first
separator, the second electrode, and the second separator are
alternatingly disposed and integrally combined, one by one in a
predetermined sequence (S20); forming through holes in the first
separator and the second separator by cutting regions of the first
separator and the second separator included in the unit structure
corresponding to the through holes with a margin (S32); forming an
electrode assembly by stacking the plurality of unit structures to
allow the through holes of the adjacent unit structures to face
each another (S42); and accommodating the electrode assembly in a
pouch case and forming regions of the pouch case other than a
vertical projection plane of the electrode assembly as fused
portions (S50).
26. The method of claim 25, wherein step S50 comprises a process of
cutting a smaller area than the through hole of the first separator
and the second separator out of the region of the fused portions
corresponding to the through holes.
27. The method of claim 24, wherein the process of cutting the
fused portions is performed by laser cutting, ultrasonic cutting,
and die cutting.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the priority of Korean Patent
Application No. 10-2013-0114247 filed on Sep. 26, 2013, in the
Korean Intellectual Property Office, and Korean Patent Application
No. 10-2014-0108814 filed on Aug. 21, 2014, in the Korean
Intellectual Property Office, the disclosure of which is
incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to methods of preparing an
electrode assembly and a secondary battery, and more particularly,
to a method of preparing an electrode assembly suitable for
preparing a secondary battery having a structure that may increase
a degree of freedom in the design of a device in which the
secondary battery is installed, and a method of preparing a
secondary battery.
BACKGROUND ART
[0003] In general, the demand for secondary batteries has been
rapidly increased as technology development and demand with respect
to mobile devices have increased. Among these secondary batteries,
lithium (ion/polymer) secondary batteries having high energy
density and operating voltage as well as excellent shelf and cycle
life characteristics have been widely used as energy sources of
various electronic products as well as various mobile devices.
[0004] Referring to Korean Patent Application Laid-Open Publication
No. 2008-0052869, a structure of a general secondary battery is
disclosed, and more particularly, a structure of a pouch-type
secondary battery having a symmetric and approximately rectangular
shape is disclosed.
[0005] Typically, in terms of the use of the space of a device in
which a secondary battery is installed, the above secondary battery
having a rectangular shape is advantageous. However, in a
particular case, the secondary battery having a rectangular shape
rather constrains the use of the space of a device. For example,
smart phones are designed with an ultra thin profile for the ease
of portability, and there are many cases that the total thickness
thereof is less than 1 cm. Since a secondary battery and various
electronic components as well as a camera module must be all
installed in a limited internal space of the smart phone, the
arrangement of these components are very important. However, since
the camera module is capable of zooming in and out and includes a
plurality of lenses, it is very difficult to reduce the thickness
thereof. Also, since a high-capacity secondary battery is used for
a prolonged operation of the smart phone, it is also very difficult
to reduce the thickness of the secondary battery. Therefore, the
camera module and the secondary battery are not disposed by being
overlapped with each other, but must be disposed by being spaced
apart from each other in the internal space of the smart phone.
[0006] Since the shape of the secondary battery is limited as
described above, the installation position of each component is
inevitably limited to a particular position, particularly in a
small electronic device. As a result, the size and design of the
device is considerably limited.
[0007] As a structure capable of addressing the above limitations,
a perforated-type secondary battery has been developed in which a
hole is formed in the center thereof. Secondary batteries are
broadly categorized as a jelly-roll type; a stack and folding type,
and a stacked type according to the shape of an electrode assembly,
and the jelly-roll type and stack and folding type electrode
assemblies are not suitable for preparing the perforated-type
secondary battery.
[0008] Thus, only the stacked type electrode assembly, which is
formed by separately stacking electrodes and separators, may be
used in the perforated-type secondary battery. However, with
respect to the stacked type electrode assembly, an excessively long
period of time may be required for a process of aligning each layer
by matching each hole formed in the plurality of electrodes and
separators which constitute the electrode assembly. Even in the
case in which the electrodes and separators are stacked by matching
each hole formed in the plurality of electrodes and separators, a
case frequently occurs in which the separators are deformed during
a process of pressurizing or heating the electrodes and separators
to change the position and shape of the hole. As a result, the
perforated-type secondary battery is only at the level of idea and
has not been commercialized yet.
SUMMARY OF THE INVENTION
[0009] The present invention provides a method of preparing an
electrode assembly suitable for preparing a secondary battery
having a structure that may increase a degree of freedom in the
design of a device in which the secondary battery is installed, and
a method of preparing a secondary battery.
[0010] According to an aspect of the present invention, there is
provided a method of preparing an electrode assembly including the
steps of: forming recessed portions recessed from edges of a first
electrode and a second electrode toward inner sides thereof (S11);
forming a unit structure having a four-layer structure, in which
the first electrode, a first separator, the second electrode, a
second separator are sequentially stacked, or a structure in which
the four-layer structures are repeatedly stacked, or having the
four-layer structure or a structure, in which the four-layer
structures are repeatedly arranged, by stacking two kinds or more
of radical units, in which the first electrode, the first
separator, the second electrode, and the second separator are
alternatingly disposed and integrally combined, one by one in a
predetermined sequence (S20); forming recessed portions in the
first separator and the second separator by cutting regions of the
first separator and the second separator included in the unit
structure corresponding to the recessed portions with a margin
(S31); and forming an electrode assembly by stacking the plurality
of unit structures to allow the recessed portions of the adjacent
unit structures to face each another (S41).
[0011] According to another aspect of the present invention, there
is provided a method of preparing an electrode assembly including
the steps of: forming through holes at inner sides of a first
electrode and a second electrode (S12); forming a unit structure
having a four-layer structure, in which the first electrode, a
first separator, the second electrode, a second separator are
sequentially stacked, or a structure in which the four-layer
structures are repeatedly stacked, or having the four-layer
structure or a structure, in which the four-layer structures are
repeatedly arranged, by stacking two kinds or more of radical
units, in which the first electrode, the first separator, the
second electrode, and the second separator are alternatingly
disposed and integrally combined, one by one in a predetermined
sequence (S20); forming through holes in the first separator and
the second separator by cutting regions of the first separator and
the second separator included in the unit structure corresponding
to the through holes with a margin (S32); and forming an electrode
assembly by stacking the plurality of unit structures to allow the
through holes of the adjacent unit structures to face each another
(S42).
[0012] According to another aspect of the present invention, there
is provided a method of preparing a lithium secondary battery
including the steps of: forming recessed portions recessed from
edges of a first electrode and a second electrode toward inner
sides thereof (S11); forming a unit structure having a four-layer
structure, in which the first electrode; a first separator, the
second electrode, a second separator are sequentially stacked, or a
structure in which the four-layer structures are repeatedly
stacked, or having the four-layer structure or a structure, in
which the four-layer structures are repeatedly arranged, by
stacking two kinds or more of radical units, in which the first
electrode, the first separator, the second electrode, and the
second separator are alternatingly disposed and integrally
combined, one by one in a predetermined sequence (S20); forming
recessed portions in the first separator and the second separator
by cutting regions of the first separator and the second separator
included in the unit structure corresponding to the recessed
portions with a margin (S31); forming an electrode assembly by
stacking the plurality of unit structures to allow the recessed
portions of the adjacent unit structures to face each another
(S41); and accommodating the electrode assembly in a pouch case and
forming regions of the pouch case other than a vertical projection
plane of the electrode assembly as fused portions (S50).
[0013] According to another aspect of the present invention, there
is provided a method of preparing a lithium secondary battery
including the steps of: forming through holes at inner sides of a
first electrode and a second electrode (S12); forming a unit
structure having a four-layer structure, in which the first
electrode, a first separator, the second electrode, a second
separator are sequentially stacked, or a structure in which the
four-layer structures are repeatedly stacked, or having the
four-layer structure or a structure, in which the four-layer
structures are repeatedly arranged, by stacking two kinds or more
of radical units, in which the first electrode, the first
separator, the second electrode, and the second separator are
alternatingly disposed and integrally combined, one by one in a
predetermined sequence (S20); forming through holes in the first
separator and the second separator by cutting regions of the first
separator and the second separator included in the unit structure
corresponding to the through holes with a margin (S32); forming an
electrode assembly by stacking the plurality of unit structures to
allow the through holes of the adjacent unit structures to face
each another (S42), and accommodating the electrode assembly in a
pouch case and forming regions of the pouch case other than a
vertical projection plane of the electrode assembly as fused
portions (S50).
[0014] According to the present invention, a method of preparing an
electrode assembly suitable for preparing a secondary battery
having a structure that may increase a degree of freedom in the
design of a device in which the secondary battery is installed, and
a method of preparing a secondary battery may be provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The following drawings attached to the specification
illustrate preferred examples of the present invention by example,
and serve to enable technical concepts of the present invention to
be further understood together with detailed description of the
invention given below, and therefore the present invention should
not be interpreted only with matters in such drawings.
[0016] FIG. 1 is a plan view of electrodes;
[0017] FIG. 2 is a plan view of electrodes in which recessed
portions according to a first embodiment are formed;
[0018] FIG. 3 is an exploded perspective view of a unit structure
according to the first embodiment including the electrodes, in
which the recessed portions are formed, and separators in which
recessed portions are not formed;
[0019] FIG. 4 is a plan view of the unit structure according to the
first embodiment including the electrodes, in which the recessed
portions are formed, and separators in which recessed portions are
not formed;
[0020] FIG. 5 is a plan view of a unit structure according to the
first embodiment in which recessed portions are formed in
separators;
[0021] FIG. 6 is a perspective view of an electrode assembly
according to the first embodiment in which the plurality of unit
structures of FIG. 5 are stacked;
[0022] FIG. 7, as an exploded view of an electrode assembly
according to a modified embodiment of the first embodiment in which
a plurality of unit structures is stacked, is a side view taken
from the side of a recessed portion of the electrode assembly;
[0023] FIG. 8 is a plan view of electrodes, in which through holes
are formed, according to a second embodiment;
[0024] FIG. 9 is a plan view of a unit structure according to the
second embodiment including the electrodes, in which the through
holes are formed, and separators in which through holes are not
formed;
[0025] FIG. 10 is a plan view of a unit structure according to the
second embodiment in which through holes are formed in
separators;
[0026] FIG. 11 is a perspective view of an electrode assembly
according to the second embodiment in which the plurality of unit
structures of FIG. 10 are stacked;
[0027] FIG. 12, as an exploded view of an electrode assembly
according to a modified embodiment of the second embodiment in
which a plurality of unit structures is stacked, is a vertical
cross-sectional view taken through through hole portions of the
electrode assembly;
[0028] FIG. 13, as a plan view of a secondary battery according to
the first embodiment, illustrates a state in which a fused portion
corresponding to the recessed portion is not cut off;
[0029] FIG. 14 illustrates a state in which the fused portion
corresponding to the recessed portion is cut off from the secondary
battery of FIG. 13;
[0030] FIG. 15, as a plan view of a secondary battery according to
the second embodiment, illustrates a state in which a fused portion
corresponding to the through hole is not cut off;
[0031] FIG. 16 illustrates a state in which the fused portion
corresponding to the through hole is cut off from the secondary
battery of FIG. 15;
[0032] FIG. 17 is a side view illustrating a first structure of a
unit structure included in an electrode assembly that is prepared
by a method of preparing an electrode assembly according to the
present invention;
[0033] FIG. 18 is side view illustrating a second structure of a
unit structure included in an electrode assembly that is prepared
by a method of preparing an electrode assembly according to the
present invention;
[0034] FIG. 19 is a process diagram illustrating a process f
preparing a unit structure according to the present invention;
[0035] FIG. 20 is a side view illustrating a first structure of an
electrode assembly including unit structures and a first auxiliary
unit;
[0036] FIG. 21 is a side view illustrating a second structure of an
electrode assembly including unit structures and a first auxiliary
unit;
[0037] FIG. 22 is a side view illustrating a third structure of an
electrode assembly including unit structures and a second auxiliary
unit;
[0038] FIG. 23 is a side view illustrating a fourth structure of an
electrode assembly including unit structures and a second auxiliary
unit;
[0039] FIG. 24 is a side view illustrating a fifth structure of an
electrode assembly including unit structures, a first auxiliary
unit, and a second auxiliary unit;
[0040] FIG. 25 is a side view illustrating a sixth structure of an
electrode assembly including unit structures and a first auxiliary
unit;
[0041] FIG. 26 is a side view illustrating a seventh structure of
an electrode assembly including unit structures and a second
auxiliary unit; and
[0042] FIG. 27 is a schematic perspective view illustrating fixing
structures of an electrode assembly according to the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0043] Hereinafter, preferred embodiments of the present invention
will be described in detail with reference to the accompanying
drawings. The present invention may, however, should not be
construed as being limited to the embodiments set forth herein.
[0044] It will be understood that words or terms used in the
specification and claims shall not be interpreted as the meaning
defined in commonly used dictionaries. It will be further
understood that the words or terms should be interpreted as having
a meaning that is consistent with their meaning in the context of
the relevant art and the technical idea of the invention, based on
the principle that an inventor may properly define the meaning of
the words or terms to best explain the invention.
[0045] In the drawings, the size of each element or specific parts
constituting the element is exaggerated, omitted, or schematically
illustrated for convenience in description and clarity. Thus, the
size of each element does not entirely reflect an actual size.
Moreover, detailed descriptions related to well-known functions or
configurations will be ruled out in order not to unnecessarily
obscure subject matters of the present invention.
[0046] A method of preparing an electrode assembly according to a
first exemplary embodiment of the present invention includes the
steps of: forming recessed portions A1 recessed from edges of a
first electrode 111 and a second electrode 113 toward inner sides
thereof (S11); forming a unit structure 110 having a four-layer
structure, in which the first electrode 111, a first separator 112,
the second electrode 113, a second separator 114 are sequentially
stacked, or a structure in which the four-layer structures are
repeatedly stacked, or having the four-layer structure or a
structure, in which the four-layer structures are repeatedly
arranged, by stacking two kinds or more of radical units, in which
the first electrode 111, the first separator 112, the second
electrode 113, and the second separator 114 are alternatingly
disposed and integrally combined, one by one in a predetermined
sequence (S20); forming recessed portions A2 in the first separator
112 and the second separator 114 by cutting regions of the first
separator 112 and the second separator 114 included in the unit
structure 110 corresponding to the recessed portions A1 with a
margin (S31); and forming an electrode assembly 100 by stacking the
plurality of unit structures 110 to allow the recessed portions A1
and A2 of the adjacent unit structures 110 to face each another
(S41).
[0047] First, in order to perform step S11, the electrodes 111 and
113 illustrated in FIG. 1 are prepared, and as illustrated in FIG.
2, the recessed portion A1 may be formed from the edge of one side
of the first electrode 11 or the second electrode 113 toward the
inner side thereof. The formation of the recessed portions A1 may
be completed by cutting the electrodes 111 and 113 illustrated in
FIG. 1, but the electrodes ill and 113 having the recessed portion
A1 initially formed therein may be prepared.
[0048] Next, as illustrated in FIGS. 3 and 4, step S20 of forming
the unit structure 110 is performed by stacking the first electrode
111 and the second electrode 113 having the recessed portion A1
formed therein and the first separator 112 and the second separator
114 not having a recessed portion in the sequence of the first
electrode 111, the first separator 112, the second electrode 113,
the second separator 114. The unit structure 110 including the
plurality of stack structures may be introduced, and the unit
structure 110 may further include an auxiliary unit to be described
later.
[0049] Next, as illustrated in FIGS. 5 and 6, step S31 of forming
the recessed portions A2 in the first separator 112 and the second
separator 114 is performed by cutting the regions, which face the
recessed portions A1 formed in the electrodes ill and 113, among
entire regions of the first separator 112 and the second separator
114. The separators 112 and 114 are cut to have an area slightly
larger than the electrodes 111 and 113 so as to prevent the
electrodes 111 and 113 disposed on both sides of each of the
separators 112 and 114 from being short-circuited without passing
the separators 112 and 114. For the same reason, it is also
desirable to cut the separators 112 and 114 along a dotted line of
FIG. 4 with some margin from an outline defining the recessed
portions A1 formed in the electrodes 111 and 113 when forming the
recessed portions A2 in the separators 112 and 114.
[0050] Next, as illustrated in FIG. 6, step S41 of forming the
electrode assembly 100 is performed by stacking the unit structures
110 to allow the recessed portions A1 and A2 of the adjacent unit
structures 110 to face each another.
[0051] The recessed portions A1 and A2 formed in any one of the
unit structures 110 may have the same size as that of the recessed
portions A1 and A2 formed in the adjacent unit structure 110.
However, in order for a secondary battery to have the maximum
capacitance without interfering with components installed in a
mechanical or electronic device, the recessed portions A1 and A2
formed in any one of the unit structures 110 may have a different
size from that of the recessed portions A1 and A2 formed in the
adjacent unit structure 110.
[0052] For example, referring to FIG. 7 as a modified embodiment of
the first embodiment, it may be confirmed that a width W1 of the
recessed portions A1 formed in the electrodes 111 and 113 of the
unit structure 110 disposed at the uppermost side of the electrode
assembly 100 is the smallest, a width W2 of the recessed portions
A1 formed in the electrodes 111 and 113 of the unit structure 110
disposed in the middle of the electrode assembly 100 is the next
smallest, and a width W3 of the recessed portions A1 formed in the
electrodes 111 and 113 of the unit structure 110 disposed at the
lowermost side of the electrode assembly 100 is the largest.
[0053] The size of the recessed portions A1 formed in the
electrodes 111 and 113 may gradually increase or, on the contrary,
may gradually decrease from a top surface of the electrode assembly
100 to a bottom surface thereof. Also, the size of the recessed
portions A2 formed in the separators 112 and 114 may gradually
increase or, on the contrary, may gradually decrease from the top
surface of the electrode assembly 100 to the bottom surface
thereof.
[0054] Hereinafter, a method of preparing an electrode assembly
according to a second exemplary embodiment of the present invention
will be described.
[0055] The method of preparing an electrode assembly according to
the second exemplary embodiment of the present invention includes
the steps of: forming through holes B1 at inner sides of a first
electrode 111 and a second electrode 113 (S12); forming a unit
structure 110 having a four-layer structure, in which the first
electrode 111, a first separator 112, the second electrode 113, a
second separator 114 are sequentially stacked, or a structure in
which the four-layer structures are repeatedly stacked, or having
the four-layer structure or a structure, in which the four-layer
structures are repeatedly arranged, by stacking two kinds or more
of radical units, in which the first electrode 111, the first
separator 112, the second electrode 113, and the second separator
114 are alternatingly disposed and integrally combined, one by one
in a predetermined sequence (S20); forming through holes B2 in the
first separator 112 and the second separator 114 by cutting regions
of the first separator 112 and the second separator 114 included in
the unit structure 110 corresponding to the through holes B1 with a
margin (S32); and forming an electrode assembly 100 by stacking the
plurality of unit structures 110 to allow the through holes B1 and
B2 of the adjacent unit structures 110 to face each another
(S42).
[0056] First, in order to perform step S12, the electrodes 111 and
113 illustrated in FIG. 1 are prepared, and as illustrated in FIG.
8, the through holes B1 may be formed at the inner sides of the
first electrode 111 and the second electrode 113. The shape of the
through holes B1 is not limited to a circular shape, but the
through holes B1 may be formed in a polygonal or irregular shape.
Also, the plurality of through holes B1 may be formed in the
electrodes 111 and 113. The formation of the through holes B1 may
be achieved by cutting the electrodes 111 and 113 illustrated in
FIG. 1, but the electrodes 111 and 113 having the through hole B1
initially formed therein may be prepared.
[0057] Next, as illustrated in FIG. 9, step S20 of forming the unit
structure 110 is performed by stacking the first electrode 111 and
the second electrode 113 having the through hole B1 formed therein
and the first separator 112 and the second separator 114 not having
a through hole in the sequence of the first electrode 111, the
first separator 112, the second electrode 113, the second separator
114. The unit structure 110 including the plurality of stack
structures may be introduced, and the unit structure 110 may
further include an auxiliary unit to be described later. Although
FIG. 3 illustrates the first embodiment, the structure of the unit
structure 110 according to the second embodiment may be easily
identified when referring to FIGS. 3 and 9 because each layer
included in the unit structure 110 according to the second
embodiment is also stacked in the same manner as in FIG. 3.
[0058] Next, as illustrated in FIGS. 10 and 11, step S32 of forming
the through holes B2 in the first separator 112 and the second
separator 114 is performed by cutting the regions, which face the
through holes B1 formed in the electrodes 111 and 113, among entire
regions of the first separator 112 and the second separator 114.
The separators 112 and 114 are cut to have an area slightly larger
than the electrodes 111 and 113 so as to prevent the electrodes 111
and 113 disposed on both surfaces of each of the separators 112 and
114 from being short-circuited without passing the separators 112
and 114. For the same reason, it is also desirable to cut inner
regions of the separators 112 and 114 defined by a dotted line of
FIG. 9 along the dotted line with some margin from an outline
defining the through holes B1 formed in the electrodes 111 and 113
when forming the through holes B2 in the separators 112 and
114.
[0059] Next, as illustrated in FIG. 11, step S42 of forming the
electrode assembly 100 is performed by stacking the unit structures
110 to allow the through holes B1 and B2 of the adjacent unit
structures 110 to face each another.
[0060] Similar to the first embodiment, in the second embodiment,
the through holes B1 and B2 formed any one of the unit structures
110 may have the same size or a different size from that of the
through holes B1 and B2 formed in the adjacent unit structure
110.
[0061] For example, referring to FIG. 12 as a modified embodiment
of the second embodiment, it may be confirmed that a width D1 of
the through holes B1 formed in the electrodes 111 and 113 of the
unit structure 110 disposed at the uppermost side of the electrode
assembly 100 is the smallest, a width D2 of the through holes B1
formed in the electrodes 111 and 113 of the unit structure 110
disposed in the middle of the electrode assembly 100 is the next
smallest, and a width D3 of the through holes B1 formed in the
electrodes 111 and 113 of the unit structure 110 disposed at the
lowermost side of the electrode assembly 100 is the largest.
[0062] The size of the through holes B1 formed in the electrodes
111 and 113 may gradually increase or, on the contrary, may
gradually decrease from a top surface of the electrode assembly 100
to a bottom surface thereof. Also, the size of the through holes B2
formed in the separators 112 and 114 may gradually increase or, on
the contrary, may gradually decrease from the top surface of the
electrode assembly 100 to the bottom surface thereof.
[0063] Hereinafter, a method preparing a secondary battery
according to the first embodiment including the electrode assembly
100 according to the first embodiment will be described.
[0064] In the method of preparing a secondary battery according to
the first embodiment, step S50 of accommodating the electrode
assembly 100 prepared through step S11, step S20, step S31, and
step S41 in a pouch case 200 and forming regions of the pouch case
200 other than a vertical projection plane of the electrode
assembly 100 as fused portions 210 and 220 is further performed
(see FIGS. 13 and 14).
[0065] That is, the method of preparing a secondary battery
according to the first embodiment includes the steps of: forming
recessed portions A1 recessed from edges of a first electrode 111
and a second electrode 113 toward inner sides thereof (S11);
forming a unit structure 110 having a four-layer structure, in
which the first electrode 111, a first separator 112, the second
electrode 113, a second separator 114 are sequentially stacked, or
a structure in which the four-layer structures are repeatedly
stacked, or having the four-layer structure or a structure, in
which the four-layer structures are repeatedly arranged, by
stacking two kinds or more of radical units, in which the first
electrode 111, the first separator 112, the second electrode 113,
and the second separator 114 are alternatingly disposed and
integrally combined, one by one in a predetermined sequence (S20);
forming recessed portions A2 in the first separator 112 and the
second separator 114 by cutting regions of the first separator 112
and the second separator 114 included in the unit structure 110
corresponding to the recessed portions A1 with a margin (S31);
forming an electrode assembly 100 by stacking the plurality of unit
structures 110 to allow the recessed portions A1 and A2 of the
adjacent unit structures 110 to face each another (S41); and
accommodating the electrode assembly 100 in the pouch case 200 and
forming regions of the pouch case 200 other than the vertical
projection plane of the electrode assembly 100 as the fused
portions 210 and 220 (S50).
[0066] Descriptions overlapping with those of step S11, step S20,
step S31, and step 41 will be omitted, and step S50 will be
described.
[0067] In step S50, the expression "vertical projection plane of
the electrode assembly 100" denotes regions of the top surface and
the bottom surface of the pouch case 200 which overlap the
electrode assembly 100. Thus, the expression "regions of the pouch
case 200 other than the vertical projection plane of the electrode
assembly 100" denotes regions indicated by hatching in FIG. 13.
Eventually, the forming of the regions other than the vertical
projection plane of the electrode assembly 100 as the fused
portions 210 and 220 denotes the fusing of the regions indicated by
hatching in FIG. 13.
[0068] As described above, the formation of the recessed portions
A1 and A2 in the electrode assembly 100 is for the purpose of
increasing a degree of freedom in the design of a mechanical or
electronic device, and, in order to sufficiently achieve the
purpose, it is desirable to make the shapes of the electrode
assembly 100 and the pouch case 200 approximately the same.
[0069] Thus, step S50 may include a process of cutting a smaller
area than the recessed portions A2 of the first separator 112 and
the second separator 114 out of the region 220 of the fused
portions 210 and 220 corresponding to the recessed portions A1 and
A2, and the secondary battery at the completion of the process is
illustrated in FIG. 14.
[0070] Hereinafter, a method of preparing a secondary battery
according to the second embodiment including the electrode assembly
100 according to the second embodiment will be described.
[0071] In the method of preparing a secondary battery according to
the second embodiment, step S50 of accommodating the electrode
assembly 100 prepared through step S12, step S20, step S32, and
step S42 in a pouch case 200 and forming regions of the pouch case
200 other than a vertical projection plane of the electrode
assembly 100 as fused portions 210 and 230 is further performed
(see FIGS. 15 and 16).
[0072] That is, the method of preparing a secondary battery
according to the second embodiment includes the steps of: forming
through holes B1 at inner sides of a first electrode 111 and a
second electrode 113 (S12); forming a unit structure 110 having a
four-layer structure, in which the first electrode 111, a first
separator 112, the second electrode 113, a second separator 114 are
sequentially stacked, or a structure in which the four-layer
structures are repeatedly stacked, or having the four-layer
structure or a structure, in which the four-layer structures are
repeatedly arranged, by stacking two kinds or more of radical
units, in which the first electrode 111, the first separator 112,
the second electrode 113, and the second separator 114 are
alternatingly disposed and integrally combined, one by one in a
predetermined sequence (S20); forming through holes B2 in the first
separator 112 and the second separator 114 by cutting regions of
the first separator 112 and the second separator 114 included in
the unit structure 110 corresponding to the through holes B1 with a
margin (S32); forming an electrode assembly 100 by stacking the
plurality of unit structures 110 to allow the through holes B1 and
B2 of the adjacent unit structures 110 to face each another (S42);
and accommodating the electrode assembly 100 in the pouch case 200
and forming regions of the pouch case 200 other than the vertical
projection plane of the electrode assembly 100 as the fused
portions 210 and 230 (S50).
[0073] Descriptions overlapping with those of step S12, step S20,
step S32, and step 42 will be omitted, and step S50 will be
described.
[0074] In step S50 of the second embodiment, the expression
"vertical projection plane of the electrode assembly 100" is used
in the same meaning as that of the first embodiment, and thus, the
forming of the regions other than the vertical projection plane of
the electrode assembly 100 as the fused portions 210 and 230
denotes the fusing of the regions indicated by hatching in FIG.
15.
[0075] Also, step S50 may include a process of cutting a smaller
area than the through holes B2 of the first separator 112 and the
second separator 114 out of the region 230 of the fused portions
210 and 230 corresponding to the through holes B1 and B2, and the
secondary battery at the completion of the process is illustrated
in FIG. 16.
[0076] Regardless of the first embodiment and the second
embodiment, the process of cutting the fused portions 210, 220, and
230 in step S50 may be performed by laser cutting, ultrasonic
cutting, and die cutting.
[0077] Until now, the structure of the unit structure 110 only
including a structure, in which each layer is simply stacked in the
sequence of the first electrode 111, the first separator 112, the
second electrode 113, the second separator 114, has been briefly
described. Also, detailed process of forming the single unit
structure 110 by fixing relative positions of different layers
constituting the unit structure 110 or forming the electrode
assembly 100 including the unit structure 110 has not been
described in detail.
[0078] Thus, what process is actually used to prepare the unit
structure 110 or the structures of various electrode assemblies 100
that may be used in the present invention will be described
below.
[0079] The electrode assembly 100 prepared by the method of
preparing an electrode assembly according to the present invention
includes at least one of unit structures 110a and 110b (see FIGS.
17 and 18).
[0080] In the electrode assembly according to the present
invention, the radical unit is formed by alternatingly arranging
the electrodes and the separators. In this case, the same number of
electrodes and separators are arranged. For example, the radical
unit 110a may be formed by stacking the two electrodes 111 and 113,
and the two separators 112 and 114. In this case, the cathode and
the anode may, of course, face each other through the separator.
When the radical unit is formed like this, the electrode is
disposed at one side end of the radical unit and the separator is
disposed at the other side end of the radical unit.
[0081] The electrode assembly according to the present invention
has basic features in that the unit structure (i.e., electrode
assembly) may be formed only by stacking the radical units. That
is, the present invention has basic features in that the unit
structure may be formed by repeatedly stacking one kind of the
radical units or stacking two kinds or more of the radical units in
a predetermined sequence. In order to realize such features, the
radical unit may have the following structure.
[0082] First, the radical unit may be formed by sequentially
stacking the first electrode, the first separator, the second
electrode, and the second separator. Specifically, the radical
units 110a and 110b may be formed by sequentially stacking the
first electrode 111, the first separator 112, the second electrode
113, and the second separator 114 from a top side to a bottom side
thereof, or may be formed by sequentially stacking the first
electrode 111, the first separator 112, the second electrode 113,
and the second separator 114 from the bottom side to the top side.
Hereinafter, the radical unit having the above structure is
referred to as "first radical unit". In this case, the first
electrode 111 and the second electrode 113 are electrodes having
opposite polarities. For example, when the first electrode 111 is a
cathode, the second electrode 113 is an anode.
[0083] When the radical unit is formed by sequentially stacking the
first electrode 111, the first separator 112, the second electrode
113, and the second separator 114 as described above, a unit
structure 100a may be formed only by repeatedly stacking one kind
of the radical units 110a. Herein, the radical unit may have an
eight-layer structure or twelve-layer structure in addition to the
above four-layer structure. That is, the radical unit may have a
structure in which the four-layer structures are repeatedly
arranged. For example, the radical unit may also be formed by
sequentially stacking the first electrode, the first separator, the
second electrode, the second separator, the first electrode, the
first separator, the second electrode, and the second
separator.
[0084] Second, the radical unit may be formed by sequentially
stacking the first electrode, the first separator, the second
electrode, the second separator, the first electrode, and the first
separator, or may be formed by sequentially stacking the second
electrode, the second separator, the first electrode, the first
separator, the second electrode, and the second separator.
Hereinafter, the radical unit having the former structure is
referred to as "second radical unit", and the radical unit having
the latter structure is referred to as "third radical unit".
[0085] Specifically, the second radical unit 110c may be formed by
sequentially stacking the first electrode 111, the first separator
112, the second electrode 113, the second separator 114, the first
electrode 111, and the first separator 112 from a top side to a
bottom side thereof. Also, the third radical unit 110d may be
formed by sequentially stacking the second electrode 113, the
second separator 114, the first electrode 111, the first separator
112, the second electrode 113, and the second separator 114 from a
top side to a bottom side thereof. Conversely, the second and third
radical units may be also formed by sequentially stacking from the
bottom side to the top side.
[0086] When each one of the second radical unit and the third
radical unit is stacked, a structure is formed in which the
four-layer structures are repeatedly stacked. Thus, when each one
of the second radical unit and the third radical unit is
alternatingly and continuously stacked, a unit structure may be
formed only by stacking the second and third radical units as
illustrated in FIG. 6.
[0087] Thus, in the present invention, one kind of the radical unit
may have a four-layer structure in which the first electrode, the
first separator, the second electrode, and the second separator are
sequentially disposed, or a structure in which the four-layer
structures are repeatedly arranged. Also, in the preset invention,
when two kinds or more of the radical units are arranged one by one
in a predetermined sequence, a four-layer structure or a structure,
in which the four-layer structures are repeatedly arranged, is
formed. For example, the above-described first radical unit has a
four-layer structure, and when each one of the above-described
second radical unit and third radical unit is stacked, i.e., total
two radical units are stacked, a twelve-layer structure is formed
in which the four-layer structures are repeatedly stacked.
[0088] Thus, in the present invention, when one kind of the radical
units are repeatedly stacked or two kinds or more of the radical
units are stacked in a predetermined sequence, a unit structure
(i.e., electrode assembly) may be formed only by the stacking.
[0089] In the present invention, the unit structure is formed by
stacking the radical unit as a basic unit. That is, radical units
are first prepared and a unit structure is then prepared by
repeatedly stacking the radical units or stacking the radical units
in a predetermined sequence. Thus, in the present invention, the
unit structure may be formed only by stacking the radical units.
Therefore, in the present invention, the radical units may be very
precisely aligned. When the radical units are precisely aligned,
the electrodes and the separators may also be precisely aligned in
the unit structure. Also, since the process becomes very simple,
the present invention may significantly improve productivity of the
unit structure (electrode assembly).
[0090] The first electrode 111 included in the unit structure 110
includes a current collector and an active material layer (active
material), and both sides of the current collector are coated with
the active material layer. Similarly, the second electrode 113
included in the unit structure 110 also includes a current
collector and an active material layer (active material), and both
sides of the current collector are coated with the active material
layer.
[0091] The process of preparing the unit structure 110 may be
performed by the following continuous process (see FIG. 19). First,
a first electrode material 121, a first separator material 122, a
second electrode material 123, and a second separator material 124
are prepared. Herein, the electrode materials 121 and 123 form the
electrodes 111 and 113 by cutting to a predetermined size as
described below. The same process is also applied to the separator
materials 122 and 124. The electrode materials 121 and 123 and the
separator materials 122 and 124 may have a form of being wound on a
roll for the process automation. These materials are prepared as
described above, and the first electrode material 121 is cut to a
predetermined size by a cutter C.sub.1. The second electrode
material 123 is also cut to a predetermined size by a cutter
C.sub.2. Then, the first electrode material 121 having a
predetermined size is provided on the first separator material 122
and the second electrode material 123 having a predetermined size
is also provided on the second separator material 124. Thereafter,
these materials are supplied together to laminators L.sub.1 and
L.sub.2.
[0092] As described above, the electrode assembly 100 is formed by
repeatedly stacking the unit structures 110. However, if the
electrodes and the separators constituting the unit structures 110
are separated from each other, it may be very difficult to
repeatedly stack the unit structures 110. Thus, it is desirable
that the electrodes and the separators included in the unit
structures 110 are bonded to one other, and the laminators L.sub.1
and L.sub.2 are used to bond the electrodes and the separators to
one another. That is, the laminators L.sub.1 and L.sub.2 apply
pressure or heat and pressure to the materials to bond the
electrode materials and the separator materials to one another.
Thus, the electrode materials and the separator materials are
bonded to one another through a lamination process by using the
laminators L.sub.1 and L.sub.2, and, as a result of the bonding,
the unit structures 110 may more stably maintain their shape.
[0093] After the lamination of each layer, the first separator
material 122 and the second separator material 124 are cut to a
predetermined size by a cutter C.sub.3. The unit structure 110 may
be formed by the cutting. In addition, various tests may be
performed on the unit structure 110 if necessary. For example,
tests, such as thickness test, vision test, and short-circuit test,
may be further performed.
[0094] The process of preparing the unit structure 110 may be
performed by the above-described continuous process, but the
process of preparing the unit structure 110 is not necessarily
performed by the continuous process. That is, it is also possible
that the first electrode 111, the first separator 112, the second
electrode 113, and the second separator 114 are first cut to an
appropriate size, and the unit structure 110 is then formed by
stacking them.
[0095] Surfaces of the separators 112 and 114 or the separator
materials 122 and 124 may be coated with a coating material having
adhesiveness. In this case, the coating material may be a mixture
of inorganic material particles and a binder polymer. Herein, the
inorganic material particles may improve thermal stability. That
is, the inorganic material particles may prevent the shrinkage of
the separator at high temperature. The binder polymer may fix the
inorganic material particles, and as a result, a predetermined pore
structure may be formed between the inorganic material particles
that are fixed between the binder polymers. Due to the pore
structure, ions may smoothly move from the cathode to the anode
even if the separator is coated with the inorganic material
particles. Also, the binder polymer may stably maintain the
inorganic material particles on the separator and thus, mechanical
stability may also be improved. Furthermore, the binder polymer may
more stably bond the separator to the electrode. As a reference,
the separator may be formed of a polyolefin-based separator
material.
[0096] As illustrated in FIGS. 17 and 18, the first separator 112
has the electrodes 111 and 113 on both sides thereof, but the
second separator 114 has the electrode 113 on only one side
thereof. Thus, the both sides of the first separator 112 may be
coated with the coating material, and the only one side of the
second separator 114 may be coated with the coating material. That
is, the both sides of the first separator 112 respectively facing
the first electrode 111 and the second electrode 113 may be coated
with the coating material, and the only one side of the second
separator 114 facing the second electrode 113 may be coated with
the coating material.
[0097] It may be sufficient that the bonding by the coating
material is performed in the inside of the unit structure 110.
Thus, as described above, the only one side of the second separator
114 may be coated. However, since the unit structures 110 may also
be bonded to each other by a method such as heat pressing, both
sides of the second separator 114 may also be coated if necessary.
That is, the one side facing the second electrode 113 and the
opposite side thereto of the second separator 114 may also be
coated with the coating material. In this case, the unit structure
110 disposed on an upper side and the unit structure 110 disposed
directly thereunder may be bonded together through the coating
material on the outer surface of the second separator 114.
[0098] As a reference, in the case that the separator is coated
with the coating material having adhesiveness, it is undesirable to
directly apply pressure to the separator with a predetermined
object. The separator typically extends longer than the electrode
to the outer side. Thus, there may be an attempt to combine an end
of the first separator 112 and an end of the second separator 114
together. For example, there may be an attempt to fuse the end of
the first separator 112 and the end of the second separator 114
together by ultrasonic welding, and with respect to the ultrasonic
welding, it is necessary to directly apply pressure to an object
with a horn. However, when the pressure is directly applied to the
end of the separator with the horn, the horn may be adhered to the
separator due to the coating material having adhesiveness. As a
result, failure of the device may occur. Therefore, in the case
that the separator is coated with the coating material having
adhesiveness, it is undesirable to use a process that directly
applies pressure to the separator with a predetermined object.
[0099] The electrode assembly 100 may further include at least one
of a first auxiliary unit 130 and a second auxiliary unit 140.
First, the first auxiliary unit 130 will be described. The unit
structure 110 is formed by sequentially stacking the first
electrode 111, the first separator 112, the second electrode 113,
and the second separator 114 from a top side to a bottom side
thereof or from the bottom side to the top side. Thus, when the
electrode assembly 100 is formed by repeatedly stacking the unit
structures 110, the first electrode 111 (116, hereinafter, referred
to as "first end electrode") is disposed at an uppermost side (see
FIG. 17) or a lowermost side (see FIG. 18) of the electrode
assembly 100 (the first end electrode may be a cathode or an
anode). The first auxiliary unit 130 is further stacked on the
first end electrode 116.
[0100] Specifically, as illustrated in FIG. 20, when the first
electrode 11 is a cathode and the second electrode 113 is an anode,
a first auxiliary unit 130a may be formed by sequentially stacking
the separator 114, the anode 113, the separator 112, and the
cathode 111 from the first end electrode 116, i.e., from the first
end electrode 116 to the outer side (top side on the basis of FIG.
20). Also, as illustrated in FIG. 21, when the first electrode 11
is an anode and the second electrode 113 is a cathode, a first
auxiliary unit 130b may be formed by sequentially stacking the
separator 114 and the cathode 113 from the first end electrode 116,
i.e., from the first end electrode 116 to the outer side. In the
electrode assembly 100, as illustrated in FIG. 20 or 21, the
cathode may be disposed at the outermost side of the first end
electrode 116 due to the first auxiliary unit 130.
[0101] In general, an electrode includes a current collector and an
active material layer (active material), and both sides of the
current collector are coated with the active material layer.
Accordingly, on the basis of FIG. 20, the active material layer
disposed under the current collector among the active material
layers of the cathode may react with the active material layer
disposed above the current collector among the active material
layers of the anode by the medium of the separator. When the unit
structures 110 are formed in the same manner and the unit
structures 110 are then sequentially stacked to form the electrode
assembly 100, the first end electrode 116 disposed at the uppermost
side or the lowermost side of the electrode assembly 100 inevitably
includes the active material layers on both sides of the current
collector similar to the first electrode 111. However, when the
first end electrode has a structure in which the both sides of the
current collector are coated with the active material layer, the
active material layer disposed on the outer side among the active
material layers of the first end electrode may not react with other
active material layers. Thus, a problem occurs in which the active
material layer is wasted.
[0102] The first auxiliary unit 130 is for addressing the above
problem. That is, the first auxiliary unit 130 is formed separately
from the unit structure 110. Thus, the first auxiliary unit 130 may
include a cathode in which only one side of the current collector
is coated with the active material layer. That is, the first
auxiliary unit 130 may include the cathode in which the only one
side facing the unit structure 110 (one side facing downward on the
basis of FIG. 20) of the both sides of the current collector is
coated with the active material layer. As a result, when the
electrode assembly 100 is formed by further stacking the first
auxiliary unit 130 on the first end electrode 116, the cathode
having only one side coated may be disposed at the outermost side
of the first end electrode 116. Therefore, the problem of the waste
of the active material layer may be addressed. Since the cathode,
for example, is configured to release nickel ions, it is
advantageous for a battery capacity to dispose the cathode at the
outermost side.
[0103] Next, the second auxiliary unit 140 will be described. The
second auxiliary unit 140 basically plays the same role as the
first auxiliary unit 130. The second auxiliary unit 140 will be
described in more detail. The unit structure 110 is formed by
sequentially stacking the first electrode 111, the first separator
112, the second electrode 113, and the second separator 114 from a
top side to a bottom side thereof or from the bottom side to the
top side. Thus, when the electrode assembly 100 is formed by
repeatedly stacking the unit structures 110, the second separator
114 (117, hereinafter, referred to as "second end separator") is
disposed at an uppermost side (see FIG. 18) or a lowermost side
(see FIG. 17) of the electrode assembly 100. The second auxiliary
unit 140 is further stacked on the second end separator 117.
[0104] Specifically, as illustrated in FIG. 22, when the first
electrode 11 is a cathode and the second electrode 113 is an anode,
a second auxiliary unit 140a may be formed as the cathode 111.
Also, as illustrated in FIG. 23, when the first electrode 11 is an
anode and the second electrode 113 is a cathode, a second auxiliary
unit 140b may be formed by sequentially stacking the anode 111, the
separator 112, and the cathode 113 from the second end separator
117, i.e., from the second end separator 117 to the outer side
(bottom side on the basis of FIG. 23). Similar to the first
auxiliary unit 130, the second auxiliary unit 140 may also include
a cathode in which only one side facing the unit structure 110 (one
side facing upward on the basis of FIG. 23) of both sides of the
current collector is coated with the active material layer. As a
result, when the electrode assembly 100 is formed by further
stacking the second auxiliary unit 140 on the second end separator
117, the cathode having only one side coated may be disposed at the
outermost side of the second end separator 117.
[0105] As a reference, FIGS. 20 and 21 and FIGS. 22 and 23
exemplify the case in which the first electrode 111, the first
separator 112, the second electrode 113, and the second separator
114 are sequentially stacked from the top side to the bottom side.
Conversely, the case, in which the first electrode 111, the first
separator 112, the second electrode 113, and the second separator
114 are sequentially stacked from the bottom side to the top side,
may also be described in the same way as described above. The first
auxiliary unit 130 and the second auxiliary unit 140 may further
include a separator at the outermost side if necessary. For
example, in the case that it is necessary for the cathode disposed
at the outermost side to be electrically insulated from the case,
the first auxiliary unit 130 and the second auxiliary unit 140 may
further include a separator at the outer side of the cathode. For
the same reason, as illustrated in FIG. 22, a separator may be
further included in the cathode that is exposed to a side opposite
to a side on which the second auxiliary unit 140 is stacked (i.e.,
uppermost side of the electrode assembly 100 of FIG. 22).
[0106] It is desirable to form the electrode assemblies 100 as
illustrated in FIGS. 24 to 26. First, an electrode assembly 100e
may be formed as illustrated in FIG. 24. The unit structure 110b
may be formed by sequentially stacking the first electrode 111, the
first separator 112, the second electrode 113, and the second
separator 114 from the bottom side to the top side. In this case,
the first electrode 111 may be a cathode and the second electrode
113 may be an anode. A first auxiliary unit 130c may be formed by
sequentially stacking the separator 114, the anode 113, the
separator 112, and the cathode 111 from the first end electrode
116, i.e., from the top side to the bottom side on the basis of
FIG. 24. In this case, the active material layer may be formed only
on one side of the cathode 111 of the first auxiliary unit 130c
facing the unit structure 110b.
[0107] Also, a second auxiliary unit 140c may be formed by
sequentially stacking the cathode 111 (first cathode), the
separator 112, the anode 113, the separator 114, and a cathode 118
(second cathode) from the second end separator 117, i.e., from the
bottom side to the top side on the basis of FIG. 24. In this case,
the active material layer may be formed only on one side of the
cathode 118 (second cathode) disposed at the outermost side of the
cathodes of the second auxiliary unit 140c facing the unit
structure 110b. As a reference, it is advantageous for the
alignment of the unit structure when the auxiliary unit includes
the separator.
[0108] Next, an electrode assembly 100f may be formed as
illustrated in FIG. 25. The unit structure 110b may be formed by
sequentially stacking the first electrode ill, the first separator
112, the second electrode 113, and the second separator 114 from
the bottom side to the top side. In this case, the first electrode
111 may be a cathode and the second electrode 113 may be an anode.
A first auxiliary unit 130d may be formed by sequentially stacking
the separator 114, the anode 113, and the separator 112 from the
first end electrode 116. In this case, the second auxiliary unit
may not be included. As a reference, the anode may react with an
aluminum layer of the pouch case 200 due to a potential difference.
Thus, it is desirable for the anode to be insulated from the pouch
case 200 through the separator.
[0109] Finally, an electrode assembly 100g may be formed as
illustrated in FIG. 26. The unit structure 110c may be formed by
sequentially stacking the first electrode 111, the first separator
112, the second electrode 113, and the second separator 114 from
the top side to the bottom side. In this case, the first electrode
111 may be an anode and the second electrode 113 may be a cathode.
A second auxiliary unit 140d may be formed by sequentially stacking
the anode 111, the separator 112, the cathode 113, the separator
114, and an anode 119 from the second end separator 117. In this
case, the first auxiliary unit may not be included.
[0110] Hereinafter, a fixing structure of the electrode assembly
100 according to the present invention will be described with
reference to FIG. 27.
[0111] The electrode assembly 100 according to the present
invention may further include a fixing part T1 fixing a side or a
front side of the unit structure 110 or the electrode assembly 100
having a structure in which the unit structures 110 are
stacked.
[0112] That is, in order to secure the stability of the stack
structure, the side of the electrode assembly 100 may be fixed by
using a separate member, and the fixing part may be realized by a
method of taping the font side of the stacked electrode assembly
100 as illustrated in FIG. 27(a), or may be realized as a fixing
part T2 fixing only the side of the electrode assembly 100 as
illustrated in FIG. 27(b). Also, with respect to FIGS. 27(a) and
27(b), a polymer tape may be used as the fixing part.
[0113] While the present invention has been shown and described in
connection with the exemplary embodiments, it will be apparent to
those skilled in the art that modifications and variations can be
made without departing from the spirit and scope of the invention
as defined by the appended claims.
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